Solid-form additive systems dispersible in aqueous media

ABSTRACT

Solid form additive systems which are dispersible in aqueous media are disclosed, as are methods for preparing such additive systems and methods for dispersing such additive systems in aqueous media. Also disclosed are methods for applying additives to polymeric particles and the polymeric particles treated by such methods.

This is a divisional application of copending application Ser. No.07/513,389 filed on Apr. 23, 1990, now U.S. Pat. No. 5,153,024, and acontinuation-in-part of application Ser. No. 392,759, filed Aug. 11,1989, now U.S. Pat. No. 5,204,022 which is incorporated herein byreference in its entirety.

DESCRIPTION

1. Field of Invention

This invention relates to solid form additive systems which aredispersible in aqueous media. In one aspect, the present inventionrelates to the preparation of such additive systems. In another aspect,the present invention relates to methods of applying additives topolymeric particles. In a further aspect, the present invention relatesto polymeric particles treated by such methods.

2. Background of the Invention

Known methods of introducing additives to polymeric particles includedry blending the materials, melting, and compounding the melted blendwith extruders and pelletizing or powdering to the desired physicalform. The additives employed to treat polymeric particles includeantioxidants, processing aids, slip agents, antiblocking agents,antistatic agents, lubricants, UV stabilizers, coupling agents andcolorants.

Another method of introducing additives to polymeric particles is tocontact such particles with additive at the extruder hopper during enduse processing. Additives such as colorants, slip agents, processingaids, blowing agents, and others are introduced to virgin polymericparticles at this stage usually in concentrate form. In many instances,difficulty is encountered in metering the exact amounts of additiveconcentrate necessary to do a specific job. This is especially true foradditives such as processing aids and external lubricants which are usedat very low levels and usually cannot be added in a concentrate form.

Some polymers are presently being manufactured with technology that doesnot lend itself to such techniques as melt compounding and pelletizing.Many polymers such as high density polyethylene, linear low densitypolyethylene, and polypropylene emerge from the polymerization reactorin a dry granular form, i.e., in a form similar to that of a fluidizedbed system. Presently, additives for these polymers must be introducedby melting, compounding, and then pelletizing. This extra step increasesthe cost of such polymer manufacturing operations and can adverselyaffect the properties of such polymers.

Another method of coating polymeric particles with additives isdisclosed in Japanese Patent 56-021815, issued to Tokoyama Soda. Thispatent teaches contacting polypropylene granules with a dispersion ofadditives in a solvent, followed by removal of the solvent. While somestabilization is thereby imparted to the coated polypropylene granules,the treated pellets have severe static electricity problems whensubsequently processed, such as for example, by extrusion.

It would be desirable to have available a simple process for applyingadditives to polymeric particles in order to enhance the stability ofthe particles without adversely affecting the physical properties andprocessability of the treated particles. Typical additives employed fortreating polymeric particles have been applied using organic solventssince such additives are typically insoluble in water. Due to the everincreasing cost of organic solvents, the high cost of solvent recoverysystems, as well as the toxicity and explosive nature of organicsolvents, plus the strict air-quality controls imposed by federalregulations, there is a great deal of motivation for users of polymeradditives to switch to water as the solvent of choice for applying suchadditives to polymeric particles.

Yet another prior art process for the application of additives topolymeric particles involves the preparation of aqueous emulsions ofadditives, as disclosed, for example, in Patent Cooperation TreatyDocument WO 86/04909. This process also discloses coating of polymericparticles by employing an aqueous emulsion or dispersion of additives,such as antioxidants, thermal stabilizing agents, colorants, and thelike. These aqueous emulsions or dispersions can be applied by spray,wipe, dip systems, or the like to coat the polymeric particles beforetheir normal drying or degassing operations.

While the latter application system represents an advance in the stateof the art by replacing the need for organic solvents with aqueous-basedapplication systems, the main disadvantage of this aqueous applicationsystem is that it contains substantial quantities of water, whichrequires special handling and shipping of the aqueous emulsions ordispersions. For example, these emulsions or dispersions tend to freezewhen exposed to extremely cold temperatures. Unfortunately, merelyheating the frozen emulsion or suspension does not always result in there-formation of stable emulsions or dispersions. Thus, exposure totemperature extremes and long term storage can cause problems inprocessing these aqueous emulsions or dispersions when it is attemptedto apply these additive systems to polymer particles.

Copending application Ser. No. 392,759, filed Aug. 11, 1989, now U.S.Pat. No. 5,204,022, discloses a process for preparation ofwater-dispersible additives in solid form wherein a grinding step isrequired to achieve the additives in solid powder form. If the meltingtemperature of the additives is less than 100° C., cryogenic grinding isneeded to obtain additives in powder form. The cryogenic grinding iscostly. Therefore, it would be desirable to develop a process whicheliminates the need for cryogenic grinding of the additives with meltingtemperatures less than 100° C. in order to obtain additives in fineparticle form.

In order to overcome the limitations cited above, it would be desirableto prepare additive systems for the treatment of polymer particleswherein the additive systems can be handled in solid form, are readilywater dispersible to produce aqueous application systems useful for thetreatment of polymer particles, and eliminate the need for cryogenicgrinding.

SUMMARY OF THE INVENTION

In accordance with the present invention, a wide range of organicadditives, such as antioxidants, thermal stabilizers, colorants, or thelike, can be rendered water dispersible. Additional additivescontemplated for use in the practice of the present invention includelubricants, mold release agents, antistatic agents, and the like. Thewater dispersible additive systems of the invention are easily handledbecause of their solid, typically free-flowing form. The waterdispersible additive systems of the invention (alternatively referred toherein as "solid emulsions") can be readily dispersed in water toproduce an aqueous emulsion or dispersion which can be used to coatpolymeric particles before performing normal drying or degassingoperations which are typically employed in normal polymer preparationand treatment environment. Coating of polymeric particles can beaccomplished employing a variety of techniques, e.g., employing spray,wipe or dip systems.

The water dispersible additive systems of the invention can beformulated for treating a wide variety of polymeric particle materialswhich can then be formed into articles made from such polymer particles.The resulting articles can be used in a wide range of applications,e.g., as film or packaging for food, medicine, and the like.

Polymers which emerge from a polymerization reactor in particle formwould substantially benefit from the application of such solid emulsionscontaining polymer additives such as antioxidants. The solid emulsionsof the invention are typically applied to polymer particles by preparingan aqueous suspension of the solid emulsion and the polymer particleswhich facilitate wetting or coating of the polymer particles by thepolymer additives, followed by drying to remove water. This means ofintroducing additives would eliminate melt compounding, lower productionenergy requirements, and minimize heat history on the polymer particles.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, there is provided a method forrendering at least one meltable polymer additive having a meltingtemperature no higher than 100° C. and, optionally, one or more highermelting polymer additives, dispersible in aqueous media, said methodcomprising:

a) heating said additive to a temperature sufficient to produce a meltphase,

b) combining the resulting melt phase, at a temperature sufficient tomaintain a melt phase, with at least one surfactant having a lowhydrophobic-lipophobic balance value and at least one surfactant havinga high hydrophobic-lipophobic balance value, wherein said combining iscarried out under sufficient agitation to provide a homogeneous mixedmelt,

c) contacting the homogeneous melt phase obtained from step b) with asufficient amount of water and under sufficient agitation andtemperature to result in a water-in-oil emulsion, and

d) allowing the water-in-oil emulsion obtained from step c) to cool soas to obtain a water dispersible encapsulated solid material in powderform having a particle size of about 5.0 to about 1000.0 μm.

In accordance with another embodiment of the present invention, thesurfactant having a high hydrophobic-lipophobic balance value iscontacted with said polymer additive after performance of step d),rather than in step (b).

In accordance with yet another embodiment of the present invention,there is provided an encapsulated composition of matter dispersible inaqueous medium (i.e., a solid emulsion), said composition comprising:

i) one or more water insoluble, meltable polymer additives and,optionally, one or more higher melting, water insoluble polymeradditives, wherein substantially all of said polymer additives have aparticle size of less than about 40 μm,

ii) at least one low hydrophobic-lipophobic balance value surfactant,wherein said surfactant is adsorbed on the surface of said waterinsoluble polymer additive particles, and

iii) at least one high hydrophobic-lipophobic balance value surfactant,

wherein said composition is in powder form having a particle size ofabout 5.0 to about 1000.0 μm and contains about 2.0 to about 40.0 weight% of encapsulated water.

In accordance with still another embodiment of the present invention,there is provided a process for dispersing water insoluble polymeradditives in aqueous medium by contacting the above-described solidemulsion compositions with an aqueous medium under conditions ofagitation and for a time sufficient to wet the composition with water.

In accordance with a further embodiment of the present invention, thereis provided a method of applying additives to polymeric particlescomprising contacting such particles with the above-described aqueousemulsion or dispersion containing the solid emulsion and, optionally,drying the resulting particles.

In accordance with a still further embodiment of the present invention,there are provided stabilized polymer particles treated by theabove-described method.

The polymer additives employed in the practice of the present inventionmay be selected from antioxidants, e.g., tetrakis[methylene3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)-propionate]methane, octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-(hydroxybenzyl)benzene,bis(2,4-di-t-butyl-phenyl) pentaerythritol diphosphite, tris(monononylphenyl) phosphite, 4,4'-butylidene-bis(5-methyl-2-t-butyl)phenol,tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, tris-nonylphenylphosphite; distearyl pentaerythritol diphosphite;tetrakis-(2,4-di-t-butylphenyl)-4,4'-biphenylylene-diphosphonite;tris-(2,3-di-t-butylphenyl) phosphite; butylated hydroxy toluene;dicetyl thiodipropionate; dimyristyl thiodipropionate;poly(1,4-cyclohexylenedimethylene-3,3'-thiodipropionate (partiallyterminated with stearyl alcohol); and the like; coupling agents, e.g.,silanes; titanates; chromium complexes; low molecular weight polyolefins(with carboxylic moieties); high molecular weight polyolefins andacrylates (with carboxylic moieties); chlorinated paraffins; and thelike; antistatic agents, e.g., glycerol monostearates; ethyoxylatedamines; polyethylene glycol; quaternary ammonium compounds (salts); andthe like; nucleating agents, e.g., sodium benzoate; diphenyl phosphinicacid (including magnesium, sodium, calcium, aluminum salts); phenylphosphinic acid (including salts); phenyl phosphorous acid (includingsalts); and the like; metal deactivators, e.g., oxalyl bis(benzylidene,hydrazide); 2,2'-oxamido bis-(ethyl3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; and the like;lubricants/slip agents/antiblocking agents, e.g., diatomaceous silica(earth); talc; clay; metallic stearates; alkyl bisstearamids; glycerolmonostearates; polyethylene glycol; erucamid; oleamid, and the like; UVinhibitors, e.g., 2-hydroxy-4-octoxybenzophenone;2-hydroxy-4-isooctoxybenzophenone; 4-hydroxy-4-n-dodecyloxybenzophenone;2-(3-di-t-butyl-2-hydroxy-5-methylphenyl-5-chlorobenzotriazole; 2-(2-hydroxy-3,5-di-t-amylphenyl) benzotriazole; p-t-butylphenyl salicylate;2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate; nickelbis-ortho-ethyl(3,5-di-t-butyl-4-hydroxybenzyl)-phosphonate;2,2',6,6'-tetramethyl-4-piperidinyl sebacate, and the like; flameretardants, e.g., decabromodiphenyl oxide; dodecachlorodimethanedibenzocyclooctane; ethylene bis-dibromo norbornane dicarboximide;ethylene bis-tetrabromophthalimide; antimony trioxide, and the like;biocides, e.g., methyl paraben, ethyl paraben, propyl paraben,halogenated alkyl organic compounds, transition metal carbamate salts,and the like; as well as mixtures of any two or more of the abovementioned classes of compounds, or mixtures of two or more compoundsfrom within a given class of compound.

In the process for producing the solid emulsions of the invention,temperatures sufficient to produce a melt phase, as contemplated by theinvention method (i.e., for step a)), can vary widely. Since manydifferent additives can be processed in accordance with the presentinvention, a melt phase can be obtained with some additives attemperatures as low as about 30° C.; however, at least one additive willrequire a temperature no higher than 100° C. to obtain a melt phase.Preferably, temperatures employed to produce a melt phase from thecombination of additives will fall in the ranges of, for example, about0° C. up to 100° C., about 0° C. to about 80° C., and about 0° C. toabout 40° C.

Of the polymer additives contemplated for use in the practice of thepresent invention, those referred to as "meltable polymer additives" arethose which melt without substantial levels of degradation to produce amelt phase having a melt viscosity in the range of about 1-1000 cp whensubjected to temperatures sufficient to produce a melt phase. Preferredmeltable polymer additives are those which produce a melt phase having amelt viscosity in the range of 1-500 cp when heated to temperaturessufficient to produce a melt phase (but no higher than 100° C.).

Higher melting polymer additives contemplated for optional use in thepractice of the present invention are materials which require elevatedtemperatures to melt or which suffer from substantial levels ofdegradation upon exposure to elevated temperatures. Such additives arealso characterized by their ability to be dispersed or dissolved in themelt phase produced by the meltable polymer additive.

The hydrophobic-lipophobic balance of a surfactant is an expression ofthe balance of the size and strength of the hydrophilic (polar) and thelipophilic (non-polar) groups of the surfactant.

As used herein, the term "low hydrophobic-lipophobic balance valuesurfactants" refers to surfactants having a hydrophobic-lipophobicbalance value less than about 9, while the term "highhydrophobic-lipophobic balance value surfactant" refers to surfactanthaving a hydrophobic-lipophobic balance value of greater than about 9.Preferably, low hydrophobic-lipophobic balance value surfactant employedin the practice of the present invention will have ahydrophobic-lipophobic balance value falling in the range of about 2 upto 8, while preferred high hydrophobic-lipophobic balance valuesurfactants employed in the practice of the present invention will havea hydrophobic-lipophobic balance value of at least about 10.

Hydrophobic-lipophobic balance values can be determined in a variety ofways. For example, hydrophobic-lipophobic balance numbers for certaintypes of nonionic agents, such as polyoxyethylene derivatives of fattyalcohols and polyhydric alcohol fatty acid esters, including those ofpolyglycols, can be calculated with the aid of the following equation:##EQU1## where S is the saponification number of the ester and A is theacid number of the acid. Thus, for a glyceryl monostearate with S=161and A=198, this equation gives a hydrophobic-lipophobic balance valuefor this material of 3.8.

For other surfactants such as esters of tall oil and rosin, bees wax,lanolin, and the like, hydrophobic-lipophobic balance values can becalculated from the equation: ##EQU2## where E is the weight percentageof oxyethylene content and P is the weight percentage of the polyhydricalcohol content.

While the above formulas are satisfactory for many surfactants, thehydrophobic-lipophobic balance values for many surfactants must beestimated by experimental methods. The experimental method ofhydrophobic-lipophobic balance value determination entails blending theunknown surfactant in varying ratios with a surfactant having a knownhydrophobic-lipophobic balance value, then using the blend to emulsifyan oil for which the hydrophobic-lipophobic balance required to emulsifythe oil (the "required HLB") is known. The blend which performs the bestis deemed to have a hydrophobic-lipophobic balance value approximatelyequal to the required HLB of the oil, so that the hydrophobic-lipophobicbalance value for the unknown material can be calculated.

A rough approximation of the hydrophobic-lipophobic balance value for arange of surfactants can be obtained by evaluation of the watersolubility of the particular surfactant as summarized in the followingtable:

    ______________________________________                                        Behavior When Added to Water                                                                    HLB Range                                                   ______________________________________                                        No dispersibility in water                                                                        1-4                                                       Poor dispersion     3-6                                                       Milky dispersion after vigorous                                                                   6-8                                                       agitation                                                                     Stable milky dispersion (upper                                                                     8-10                                                     end almost translucent)                                                       From translucent to clear                                                                         10-13                                                     dispersion                                                                    Clear solution      13+                                                       ______________________________________                                    

Exemplary low hydrophobic-lipophobic balance value surfactantscontemplated for use in the practice of the present invention include:

mono- and diglycerides,

sorbitan fatty acid esters,

polyoxyethylene sorbitol esters,

polyoxyethylene alcohols,

ethoxylated alkylphenols,

ethoxylated alcohols,

polyalkylene glycol ethers,

phosphated mono- and diglycerides,

citric acid esters of monoglycerides,

diacetylated tartaric acid esters of monoglycerides,

glycerol monooleate,

sodium stearoyl lactylates,

calcium stearoyl lactylates,

phospholipids, or

phosphatidyl ethanolamine,

as well as mixtures of any two or more thereof.

Exemplary high hydrophobic-lipophobic balance value surfactantscontemplated for use in the practice of the present invention include:

glycerol monostearate,

polyoxyethylene sorbitan fatty acid esters,

polyethylene sorbitol esters,

polyoxyethylene acids,

polyoxyethylene alcohols,

polyoxyethylene alkyl amines,

alkyl aryl sulfonates, or

ethoxylated alkylphenols,

as well as mixtures of any two or more thereof.

The amount of surfactant employed in the practice of the presentinvention can vary widely. Typically, the total amount of surfactantsemployed will fall in the range of about 0.5 up to 40.0 wt %, based onthe total weight of the final composition (i.e., the solid emulsion);with the total amount of surfactants falling in the range of about 1.0up to 10.0 wt % being preferred.

The weight ratio of low hydrophobic-lipophobic balance value surfactantsto high hydrophobic-lipophobic balance value surfactants employed in thepractice of the present invention can vary widely. Typically, the weightratio of low-hydrophobic-lipophobic balance value surfactant to highhydrophobic-lipophobic balance value surfactant will fall in the rangeof about 0.1 up to 10:1; with weight ratios in the range of about 0.5 upto 2:1 being preferred.

The components of the invention composition can be combined in most anyconvenient manner. Thus, all components can be combined, then heated toproduce a melt, or the meltable component can be heated alone, followedby addition of the other components, and so on. It is presentlypreferred that all additives contemplated for a given composition becombined and melted, then the low hydrophobic-lipophobic balance valuesurfactant(s) added, followed by addition of the highhydrophobic-lipophobic balance value surfactant(s).

Agitation of the melt phase is desirable to aid production of asubstantially homogeneous melt. Agitation can be provided by anysuitable means, such as mechanical stirring, shaking, and the like.

The combination is maintained under melt conditions and agitated for atime sufficient to produce a substantially homogeneous melt phase.

The amount of water typically used to form the water-in-oil emulsion(i.e., for step c)) is about 2.0 to about 40.0 weight %, preferablyabout 5.0 to about 20.0 weight %, based on the total weight of theemulsion. The water added to form the water-in-oil emulsion canoptionally contain up to 50.0 weight % of an additional additive such asantioxidants, processing aids, slip agents, antiblocking agents, orlubricants. The temperature during formation of the water-in-oilemulsion (i.e., during step c)) is about the same as used for step b).Thus, the temperature used is sufficient to melt at least the lowestmelting additives present and preferably is about 5° C. up to 20° C.above the melting point of the lowest melting polymer additive present,but in no case is higher than 100° C. The rate of cooling and the amountof agitation for step d) is that amount sufficient to form anencapsulated polymer material in powder form having a particle size ofabout 5.0 to about 1000.0 μm, preferably about 5.0 to about 500.0 μm.Therefore, the need for additional grinding or other particle sizereduction methodology is eliminated and the encapsulated particlesproduced are easily dispersible in water or an aqueous medium. A typicalrate of cooling is about 10° C./hour to about 100° C./hour. On coolingthe melted ingredients convert to a fine particle form containing waterencapsulated in the melt phase which on cooling solidify and produce thepolymer material in powder form, i.e., produce the solid emulsions ofthe invention.

The solid emulsions prepared in accordance with the present inventionmay contain a variety of emulsifiable waxes, e.g., an emulsifiablepolyethylene wax having a density of 0.939, a melt viscosity of 250 cpat 125° C. and an acid number of 16. The emulsifiable wax, if present,is added to the melt phase of the polymer additive. If present, said waxwill be typically in an amount of about 1 to about 50 weight percent,based on the weight of the polymer additive(s). The emulsifiable waxcontemplated for use in the practice of the present invention may be anywax which can be readily emulsified, for example, emulsifiablepolyolefin waxes such as oxidized polyolefin waxes or modifiedpolyolefin waxes. Preferred oxidized polyolefin waxes include waxeshaving a density in the range of about 0.92-0.96, melt viscosities inthe range of about 50-4,000 cp at 125° C. and an acid number in therange of about 12-55. Exemplary waxes include an oxidized polyethylenewax having a density of 0.939, a melt viscosity of 250 cp at 125° C. andan acid number of 16; an oxidized polyethylene wax having a density of0.942, a melt viscosity of 900 cp at 125° C. and an acid number of 15;an oxidized polyethylene wax having a density of 0.955, a melt viscosityof 250 cp at 125° C. and an acid number of 16; and a maleatedpolypropylene wax having a density of 0.934, a melt viscosity of 400 cpat 190° C. and an acid number of 47.

The invention compositions are readily dispersed in aqueous media,typically by adding up to 50 wt % of the solid emulsion to an aqueousmedium, and agitating sufficiently to promote contact between theparticles of additive and the aqueous media. Any suitable means topromote such contacting is acceptable for the desired agitation.

When the solid emulsion produced by the present invention is dispersedin aqueous media, stable suspensions are obtained which have a particlesize of about 0.5 to about 250.0 μm, preferably about 1.0 to about 100.0μm.

Depending on factors such as the particle size of the solid emulsion tobe dispersed, the temperature of the aqueous media, the quantity ofpolymer additive(s), the quantity (and ratio) of high and lowhydrophobic-lipophobic value surfactants, and the like, the contact timerequired for dispersion of the additive(s) of the solid emulsion can beas short as a few minutes up to 3 hours or longer. Preferably, undertypical operating conditions, it will take in the range of about 0.1 upto 1 hour for complete dispersion of the additive(s).

The invention compositions (i.e., solid emulsions) can be dispersed inaqueous media in large quantities. Thus, loading of up to about 50 wt %solids in aqueous media are contemplated. Preferred loading levels fallin the range of about 5 up to 25 wt %, based on the total weight ofpolymer additive(s) and low hydrophobic-lipophobic balance valuesurfactant. Since it is frequently added separately to the aqueousmedia, the quantity of high hydrophobic-lipophobic balance valuesurfactant is indicated separately to vary in the range of about 0.1 upto 10 wt %, with quantities in the range of about 0.1 up to 1 wt % beingpreferred.

The dispersions or emulsions may also contain surfactants andemulsifiers such as commercially available Tergitol 15-S-15 [anethoxylated linear alcohol having a hydrophilic-lipophilic balance of15.4, as determined according to Griffin, W. C., Office, Dig. FederationPaint Varnish Prod. Blubs, 28 446 (1956)], and anti-foam agents such asSWS-211 (a mixture of food grade emulsifiers, 10% by wt siliconecompounds, and water). Such emulsions may also contain potassiumhydroxide, sodium tetraborate, sodium carbonate, sodium bicarbonate,calcium carbonate or magnesium carbonate, morpholine,2-amino-2-methylpropanol, tall oil fatty acid, ethylene glycol andethoxylated stearyl alcohol [commercially available as Industrol A99],and the like.

The above-described aqueous emulsions or dispersions are useful, forexample, for applying numerous polymer additives, either alone or incombination, to a wide range of polymer particles. This is readilyaccomplished by contacting the polymer particles with the abovedescribed aqueous emulsion or dispersion, e.g., by spraying thedispersion on the polymer particles, mixing polymer particles with theaqueous dispersion, and the like.

The polymer particles treated with the solid emulsions (in dispersionform) of the present invention can be any polymer that is in the form ofbeads, fine powder, pellets, and the like.

Some preferred polymeric particles include, for example, polyolefinssuch as crystalline polypropylene, low density polyethylene, highdensity polyethylene and linear low density polyethylenes. Otherpolymeric materials include, for example, polystyrene, polyesters,polyamides and the like as well as copolymers such as crystallinepropylene ethylene copolymers, rubbers such as ethylene propylene rubberand the like.

The present invention provides polymeric particles which are stabilizedin the above-mentioned unique and efficient manner.

The invention will now be described in greater detail with reference tothe following non-limiting examples.

EXAMPLES Example 1

This example illustrates the preparation of water-dispersible Irganox®1076 used as a thermal stabilizer and antioxidant for polymericparticles employing the process of the present invention. Irganox® 1076is chemically known as octadecyl3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate or octadecyl3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and supplied by Ciba-Geigy.The surfactants used were ethoxylated alkylphenols commercially known asIgepal® surfactants from GAF Corporation. An aqueous-dispersiblematerial in the solid emulsion form contained the following ingredients:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.0   53.1                                                Epolene ® E-14 10.0   10.6                                                Calcium Stearate   15.9   16.9                                                Igepal ® CO-210                                                                               1.4    1.5                                                Igepal ® CO-630                                                                               1.9    2.0                                                Water              15.0   15.9                                                ______________________________________                                    

The following procedure was used for converting water-insolubleingredients to water-dispersible solid emulsion form.

1. Heat Irganox® 1076, Epolene® E-14 and calcium stearate in a glasscontainer at 60°-70° C. using water bath or glass-col. The melt wasstirred to obtain the homogeneous melt phase.

2. Add to the melt phase a low HLB surfactant (e.g., Igepal® CO-210).The surfactant was mixed completely by stirring device.

3. Add to the melt phase (Step 2) a high HLB value surfactant (e.g.,Igepal® CO-630). The surfactant was completely mixed in the melt phaseby stirring device.

4. Water was added to the melt phase (Step 3) slowly during stirring themelt phase. A water-in-oil emulsion was obtained which contained meltphase as a continuous medium.

5. Cool the ingredients at room temperature, while continuous stirringthe melt phase. On cooling, the melted ingredients convert to the fineparticle form containing water encapsulated in the melt phase which oncooling solidify and produce solid emulsion in fine powder form.

EXAMPLE 2

This example illustrates the preparation of an aqueous suspension usingsolid emulsion obtained from the process of the present invention. Anaqueous-dispersible material prepared in accordance with Example 1 wasemployed for preparing an aqueous suspension. 20 g of solid emulsion infine powder form were dispersed in 80 g of H₂ O using magnetic stirrer.Stable suspensions were obtained. The material remained dispersed inwater for several weeks. Typical particle size of the dispersion was:

    ______________________________________                                        % Relative Volume                                                                             Particle size μm                                           ______________________________________                                        10              3.25                                                          50              9.45                                                          90              24.05                                                         ______________________________________                                    

The particle size of the additives dispersed in water is large enough topromote settling. However, no settling was observed for several days,which may be due to the density of dispersed phase close to water andthe proper selection of the surfactants.

EXAMPLE 3

Example 1 was repeated with the exception that the amount of water usedwas 22.5 g instead of 15.0 g in preparing the water-dispersibleadditives in solid emulsion form. The composition of water-dispersibleadditives was as follows:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.0   49.2                                                Epolene ® E-14 10.0    9.8                                                Calcium Stearate   15.9   15.6                                                Igepal ® CO-210                                                                               1.4    1.4                                                Igepal ® CO-630                                                                               1.9    1.9                                                Water              22.5   22.1                                                ______________________________________                                    

An aqueous dispersion was prepared in accordance with Example 2. Typicalparticle size of aqueous dispersion was:

    ______________________________________                                        % Relative Volume                                                                             Particle size (μm)                                         ______________________________________                                        10               3.70                                                         50              10.05                                                         90              25.36                                                         ______________________________________                                    

EXAMPLE 4

Example 1 was repeated with the exception that the amount of water usedwas 30.0 g instead of 15.0 g in preparing water-dispersible additives insolid emulsion form. The composition of the water-dispersible additiveswas as follows:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.0   45.8                                                Epolene ® E-14 10.0    9.2                                                Calcium Stearate   15.9   14.6                                                Igepal ® CO-210                                                                               1.4    1.3                                                Igepal ® CO-630                                                                               1.9    1.7                                                Water              30.0   27.4                                                ______________________________________                                    

The material was water-dispersible. Stable dispersions were obtained,which did not settle for several days.

EXAMPLE 5

Example 1 was repeated with the exception that the amount of wateremployed was 37.5 g instead of 15.0 g in preparing water-dispersibleadditives in solid emulsion form. The composition of water-dispersibleadditives was as follows:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.0   42.8                                                Epolene ® E-14 10.0    8.6                                                Calcium Stearate   15.9   13.6                                                Igepal ® CO-210                                                                               1.4    1.2                                                Igepal ® CO-630                                                                               1.9    1.6                                                Water              37.5   32.2                                                ______________________________________                                    

An aqueous dispersion was prepared in accordance with Example 2. Typicalparticle size of aqueous dispersion was:

    ______________________________________                                        % Relative Volume                                                                             Particle size (μm)                                         ______________________________________                                        10              3.42                                                          50              9.35                                                          90              23.22                                                         ______________________________________                                    

EXAMPLE 6

Example 1 was repeated with the exception that the Epolene® E-14 andcalcium stearate were eliminated from the formulation. Thewater-dispersible additive in solid emulsion form contains the followingingredients:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.00  80.4                                                Igepal ® CO-210                                                                               0.92   1.5                                                Igepal ® CO-630                                                                               1.25   2.0                                                Water              10.00  16.1                                                ______________________________________                                    

The solid emulsion in fine powder form was obtained, which wasdispersible in water:

EXAMPLE 7

Example 6 was repeated with the exception that the formulation includesEpolene® E-14. The water-dispersible additive obtained in the solidemulsion form has the following composition:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        Irganox ® 1076 50.0   71.8                                                Epolene ® E-14 7.5    10.8                                                Igepal ® CO-210                                                                              0.9     1.3                                                Igepal ® CO-630                                                                              1.2     1.7                                                Water              10.0   14.4                                                ______________________________________                                    

An aqueous dispersion was prepared in accordance with Example 2. Typicalparticle size of aqueous dispersion was:

    ______________________________________                                        % Relative Volume                                                                             Particle size (μm)                                         ______________________________________                                        10               4.5                                                          50              11.6                                                          90              25.9                                                          ______________________________________                                    

The stable dispersions were obtained, which did not settle for severaldays.

EXAMPLE 8

Example 6 was repeated with the exception that the amount of water usedwas 24.70 g instead of 10 g in preparing additive in solid emulsionform. On cooling, the material obtained was sticky, and water wasseparated from solid. This example illustrates that an optimum amount ofwater is required to obtain additives in fine powder form.

EXAMPLE 9

Example 6 was repeated with the exception that the amount of waterincorporated was 5.0 g instead of 10.0 g in preparing water-dispersibleadditives using the process of this invention. On cooling, the solidemulsion was obtained with larger particles as compared to particlesobtained using the formulation of Example 6. These observationsdemonstrate that an optimum amount of water is needed for obtainingadditives in fine powder form.

EXAMPLE 10

Example 6 was repeated with the exception that Arlacel® 80 was usedinstead of Igepal® CO-210 in preparing the additive in water-dispersiblesolid emulsion form. The material was easily water-dispersible, anddispersions did not settle for several days. Typical particle size ofthe aqueous dispersions was as follows:

    ______________________________________                                        % Relative Volume                                                                             Particle size (μm)                                         ______________________________________                                        10               4.7                                                          50              10.8                                                          90              24.8                                                          ______________________________________                                    

EXAMPLE 11

This example illustrates the preparation of water-dispersible distearylthiodipropionate (DSTDP) using the process of the present invention. Anaqueous dispersible material in the solid emulsion form contained thefollowing ingredients:

    ______________________________________                                                           Amount                                                     Ingredients          (g)    (%)                                               ______________________________________                                        DSTDP (Grace Co.)    50.0   77.4                                              Epolene ® E-14   7.5    11.6                                              Arlace ® 80      0.9    1.4                                               Igepal ® CO-630  1.2    1.9                                               Water                5.0    7.7                                               ______________________________________                                    

DSTDP and Epolene® E-14 were heated up to 90° C. using Glass-Col.Arlacel® 80 was added to the melt during stirring. After completemixing, Igepal® CO-630 was added while stirring the melt phase. The meltwas allowed to cool up to 80° C. At 80° C., water was added slowlyduring continuous stirring in order to obtain water-in-oil emulsion. Themelted ingredients were allowed to cool at room temperature, butstirring was continued until melt became viscous in order to minimizethe water separation from the melt phase. At room temperature, materialwas obtained in fine powder form. The stable dispersions were obtainedin water, which did not settle for several days.

EXAMPLE 12

Example 11 was repeated with the exception that the amount of waterincorporated was 10.0 g instead of 5.0 g in preparing water-dispersibleadditive in solid emulsion form. The particles were larger compared tothe material of Example 11. This example illustrates that an optimumamount of water is required to prepare solid emulsion in fine powderform.

The material obtained was dispersible in water but required more time todisperse in water compared to material with fine particles as obtainedin Example 11.

EXAMPLE 13

Example 11 was repeated with the exception that dilaurylthiodipropionate (DLTDP) was used instead of distearyl thiopropionate,and DLTDP and Epolene® E-14 were heated to 55° C. instead of 90° C. toobtain the melt phase. The water-dispersible additive contained thefollowing ingredients:

    ______________________________________                                                         Amount                                                       Ingredients        (g)    (%)                                                 ______________________________________                                        DLTDP              50.0   77.4                                                Epolene ® E-14 7.5    11.6                                                Arlacel ® 80   0.9    1.4                                                 Igepal ® CO-630                                                                              1.2    1.9                                                 Water              5.0    7.7                                                 ______________________________________                                    

The stable dispersions were obtained. Typical particle size of aqueousdispersions was:

    ______________________________________                                        % Relative Volume                                                                             Particle size (μm)                                         ______________________________________                                        10               5.21                                                         50              11.05                                                         90              26.50                                                         ______________________________________                                    

EXAMPLE 14

The water-dispersible additives prepared in accordance with Example 4were employed to stabilize polymeric particles. Aqueous dispersionscontaining 20% by weight additives (Example 4) were prepared. Thedispersions were further diluted with water to obtain 5% solids.

40 Grams of diluted aqueous dispersion was applied to 500 g ofpolypropylene pellets having a density of 0.902 and a melt flow rate of9. The amount of dispersion used was calculated to achieve the solidlevel of 0.4-0.5% solids by weight on the coated polypropylene pellets.The polypropylene pellets were placed in an oven for 15-20 minutes at60°-90° C. before starting coating. The pellets should be warm in orderto achieve good adhesion of additives employed for coating. The coatedpolypropylene pellets did not exhibit a color shift when placed in anoven for 72 hours at a temperature of 150° C.

EXAMPLE 15

Example 14 was repeated with the exception that water-dispersiblematerial of Example 10 was used instead of the material of Example 4 forcoating polypropylene pellets. The coated pellets did not exhibit acolor shift when placed in an oven for 72 hours at a temperature of 150°C.

EXAMPLE 16

Example 14 was repeated with the exception that water-dispersiblematerial of Example 13 was used instead of the material of Example 4 forcoating polypropylene pellets. The coated pellets did not exhibit acolor change when placed in an oven for 72 hours at a temperature of150° C.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

I claim:
 1. An encapsulated composition of matter dispersible in aqueousmedium, said composition comprising:i) one or more water insoluble,meltable polymer additives and, optionally, one or more higher melting,water insoluble polymer additives, wherein substantially all of saidpolymer additives have a particle size of less than about 40 μm, ii) atleast one low hydrophobic-lipophobic balance value surfactant, whereinsaid surfactant is adsorbed on the surface of said water insolublepolymer additive particles, and iii) at least one highhydrophobic-lipophobic balance value surfactant,wherein said compositionis in powder form having a particle size of about 5.0 to about 1000.0 μmand contains about 2.0 to about 40.0 weight % of encapsulated water. 2.A composition in accordance with claim 1 wherein said polymer additivesare selected from the group consisting of:thermal stabilizing agents,processing aids, colorants, antistatic agents, coupling agents, UVstabilizers, metal deactivators, nucleating agents, and flameretardants, as well as mixtures of any two or more thereof.
 3. Acomposition in accordance with claim 2 wherein said thermal stabilizingagent is an antioxidant and is selected from the group consistingof:tetrakis[methylene3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)-propionate]-methane, octadecyl3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-(hydroxybenzyl)benzene,bis(2,4-di-tert-butyl-phenyl)pentaerythritol diphosphite,tris(monononylphenyl)phosphite,4,4'-butylidene-bis(5-methyl-2-tert-butyl)phenol,tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, tris-nonylphenylphosphite, distearyl pentaerythritol diphosphite,tetrakis-(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite,tris-(2,3-di-tert-butylphenyl)phosphite, butylated hydroxy toluene,dicetyl thiodipropionate, dimyristyl thiodipropionate, andpoly(1,4-cyclohexylene-3,3'-thiodipropionate, partially terminated withstearyl alcohol,as well as mixtures of any two or more thereof.
 4. Acomposition in accordance with claim 2 wherein said processing aids areselected from the group consisting of talc, clay, diatomaceous earth,metallic s alkyl bisstearamides, glycerol monostearates, polyethyleneglycol, erucamid, and oleamid, as well as mixtures of any two or morethereof.
 5. A composition in accordance with claim 2 wherein saidcolorants are selected from the group consisting of:poly(ethyleneterephthalate) copolymerized with1,5-bis[(3-hydroxy-2,2'-dimethylpropyl)amino]anthraquinone,poly(neopentylene terephthalate) copolymerized with2,2'-(9,10-dihydro-9,10-dioxo-1,5-anthracenediyl)diimino)-bis-benzoicacid, and poly(neopentylene naphthalene-2,6-dicarboxylate) copolymerizedwith 1,5-bis[(3-hydroxy-2,2-dimethylpropyl)-amino]anthraquinone.
 6. Acomposition in accordance with claim 2 wherein said antistatic agentsare selected from the group consisting of glycerol monostearates,ethoxylated amines, polyethylene glycols, and quaternary ammoniumcompounds, as well as mixtures of any two or more thereof.
 7. Acomposition in accordance with claim 2 wherein said coupling agents areselected from the group consisting of silanes titanates, chromiumcomplexes, carboxyl-substituted polyolefins, carboxyl-substitutedacrylates, and paraffins, as well as mixtures of any two or morethereof.
 8. A composition in accordance with claim 2 wherein said UVstabilizers are selected from the group consistingof:2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-isooctoxy-benzophenone,4-hydroxy-4-n-dodecycloxybenzophenone,2-(3-di-tert-butyl-2-hydroxy-5-methylphenyl-5-chlorobenzyltriazole,2-(2-hydroxy-3,5-di-tert-amylphenyl)-benzotriazole,para-tert-butylphenyl salicylate,2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, nickelbis-ortho-ethyl(3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, and2,2',6,6'-tetramethyl-4-piperidinyl sebacate, as well as mixtures of anytwo or more thereof.
 9. A composition in accordance with claim 2 whereinsaid flame retardant is selected from the group consistingof:decabromodiphenyl oxide, dodecachlorodimethane dibenzocyclooctane,ethylene bis-dibromo norbornane dicarboxamide, ethylenebis-tetrabromophthalimide, and antimony trioxide,as well as mixtures ofany two or more thereof.
 10. A composition in accordance with claim 2wherein said metal deactivating agent is selected from the groupconsisting of:oxalyl bis-(benzylidene hydrazide), and 2,2'-oxamidobis-(ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate,as well asmixtures of any two or more thereof.
 11. A composition in accordancewith claim 2 wherein said nucleating agent is selected from the groupconsisting of sodium benzoate, diphenyl phosphinic acid, the magnesium,sodium, calcium, and aluminum salts of diphenyl phosphinic acid, phenylphosphinic acid, the magnesium, sodium, calcium, and aluminum salts ofphenyl phosphinic acid, phenyl phosphorous acid, and the magnesium,sodium, calcium, and aluminum salts of phenyl phosphorous acid, as wellas mixtures of any two or more thereof.
 12. A composition in accordancewith claim 1 wherein said surfactant having a low hydrophobic-lipophobicbalance value has a hydrophobic-lipophobic balance value which falls inthe range of about 2 up to
 8. 13. A composition in accordance with claim12 wherein said surfactant having a low hydrophobic-lipophobic balancevalue is selected from the group consisting of:mono- and diglycerides,sorbitan fatty acid esters, polyoxyethylene sorbitol esters,polyoxyethylene alcohols, ethoxylated alkylphenols, ethoxylatedalcohols, polyalkylene glycol ethers, phosphated mono- and diglycerides,citric acid esters of monoglycerides, diacetylated tartaric acid estersof monoglycerides, glycerol monooleate, sodium stearoyl lactylates,calcium stearoyl lactylates, phospholipids, and phosphatidylethanolamine,as well as mixtures of any two or more thereof.
 14. Acomposition in accordance with claim 1 containing about 1 to about 50weight percent of an emulsifiable wax, based on the weight of thepolymer additive.
 15. A process for dispersing in water one or moremeltable polymer additives and, optionally, one or more higher meltingpolymer additives, said process comprising contacting the composition ofclaim 1 with an aqueous medium under conditions of agitation and for atime sufficient to wet said composition with water.